Conventionally, as a wheel type operating vehicle in which an engine is placed in a lower traveling body, there have been structured disclosed in Japanese Unexamined Patent Publication Nos. 6-211061 and 8-118966.
At first, a description will be given of a first prior art disclosed in Japanese Unexamined Patent Publication No. 6-211061 with reference to FIGS. 6 and 7. FIG. 6 is a side elevational view of an operating vehicle described in the publication, and FIG. 7 is a plan view of a lower traveling body thereof.
In FIGS. 6 and 7, a wheel type traveling and operating vehicle 60 is structured such that an upper revolving body 63 is rotatably mounted on an upper surface of a lower traveling body 61 via a revolving circle 62, and an operating machine 64 and an operator cabin 91 are arranged in an upper portion of the upper revolving body 63. Further, a swivel joint 65 for introducing an oil pressure from the lower traveling body 61 to the upper revolving body 63 is arranged in a center portion of revolution of the revolving circle 62. A chassis frame body 71 is arranged substantially in a center of a width of vehicle body of the lower traveling body 61 in a longitudinal direction, and a front side lower portion and a rear side lower portion of the chassis frame body 71 are respectively supported by a front axle 76 in which front wheels 78 and 78 are mounted to both end portions, and a rear axle 77 in which rear wheels 79 and 79 are mounted to both end portions.
An engine 81 is positioned in an inner side of left and right frames 72 and 73 of the chassis frame body 71 so as to be close to a center of the vehicle, as shown in FIG. 7, and is arranged so that a shallow portion of an oil pan 81a in the engine 81 astride extends over the front axle 76 as shown in FIG. 6, a driving unit 66 is connected to a rear end portion of the engine 81, and a hydraulic pump 67 and a hydraulic motor 68 are mounted to a rear end surface of the driving unit 66. Further, a radiator 93 is arranged in a forward portion of the engine 81.
Next, a description will be given of a second prior art disclosed in Japanese Unexamined Patent Publication No. 8-118966 with reference to FIGS. 8 and 9. FIG. 8 is a plan view of an operating vehicle described in the publication, and FIG. 9 is a partly enlarged view of a main portion in FIG. 8. In FIGS. 8 and 9, the same reference numerals are attached to the same constituting elements as those in FIGS. 6 and 7, and a description thereof will be omitted below.
In FIGS. 8 and 9, an operating machine 74 is arranged between left and right frames 72 and 73 of a chassis frame body 71 in a wheel type traveling and operating vehicle 70 along a longitudinal axis X—X of the vehicle, and the operating machine 74 is connected to the left and right frames 72 and 73 by a pin 75 disposed in a rear portion of the vehicle so as to freely swing in a vertical direction. A stand 90 is mounted between a front wheel 78 and a rear wheel 79 and in a lower portion of the chassis frame body 71 so as to protrude left outward and right outward of the chassis frame body 71, an operator cabin 91 is mounted on an upper surface of the stand 90 in an outer portion of the left frame 72, and an engine 81 and a radiator 93 which are covered by a housing 92 are mounted in an outer portion of the right frame 73.
The engine 81 is mounted in such a manner as to make an axis of rotation C—C of a crank shaft substantially orthogonal to an axis X—X in a longitudinal direction of the vehicle and direct an output shaft side of the engine 81 toward an inner side of the vehicle, and a transfer gear box (a bevel gear output portion) 82 is connected to an end portion in a side of the output shaft of the engine 81, and further the axis of rotation is converted into an axis D—D parallel to the longitudinal axis X—X of the vehicle by bevel gears 82a and 82b within the transfer gear box 02. On the axis D—D, a hydraulic pump 83 for driving the operating machine is mounted to a rear end portion of the transfer gear box 82, a torque converter 84 and a transmission 65 are mounted in a front end portion thereof, respectively so as to be in series in the longitudinal direction. Further, a front output shaft 85a and a rear output shaft 85b of the transmission 85 are respectively connected to respective differential gear box 76a and 77a of a front axle 76 and a rear axle 77 by propeller shafts 86 and 87.
However, in the first prior art, the following problems are generated.
(1) Since the engine 81 is arranged close to the center of the vehicle rather than the front axle 76 so as to extend astride over the front axle 76 and a protruding amount of the front end portion (the radiator 93 or the like) of the vehicle extends slightly from the front end of the front wheel 78, forward operability is improved. However, there is a possibility that the operating machine 64 interferes with the radiator 93 in the front end portion of the vehicle at a time of deep excavating at the forward portion.
(3) Since the engine 81 and the driving unit 66 are connected in series in the direction of the rotational axis and are mounted within the chassis frame body 71 in the longitudinal direction, a required space from the front axle 76 to the driving unit 66 becomes long, and accordingly, in the case that a distance L2 between the axles is not large, it is impossible to arrange the position of the center of revolution (that is, the swivel joint 65) substantially in the center of the distance L2 between the axles. Accordingly, in a compact vehicle or the like, there is a case that the position of the center of revolution can not arranged substantially in the center of the distance L2 between the axles, and a difference of relative merits is generated in an operability at the front end portion of the vehicle and the rear end portion, thereby reducing the operability.
Further, in the second prior art, since the engine 81 is placed at a position in a horizontal direction of the chassis frame body 71, it is effective for a solving means against the problems in the first prior art, however, the following problems exist.
The power transmission equipment (the transfer gear box 82, the torque converter 84, the transmission 85 and the like), and the hydraulic pump 83 are arranged in the center portion in the longitudinal direction in the inner side of
the chassis frame body 71 so as to be in series in the longitudinal direction of the vehicle. Accordingly, when it is intended to apply the structure mentioned above to the wheel vehicle in which the upper revolving body is mounted, the swivel joint can be arranged only close to any one of the front and axles 76 and 77, so that it is hard to arrange the position of the center of revolution in the center between the front and rear axles 76 and 77. Further, since it is necessary to increase the longitudinal length of the chassis frame body 71, an entire length of the vehicle is increased, and a traveling property is reduced.